Transceiver system and method of using same

ABSTRACT

A transceiver is provided for wireless communication. The transceiver can include a bias source, a transformer including a primary side and a secondary side, and a switching device. During a receive mode, the primary side of the transformer is configured to receive a first signal from a first port. During a transmission mode, the primary side is configured to transmit a second signal from a second port. The switching device is configured to couple the first port to the bias source during transmission of the second signal and to couple the second port to the bias source during receipt of the first signal. The bias source can be, for example, ground.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/902,630, filed Sep. 24, 2007, (now allowed), which is a continuationof U.S. patent application Ser. No. 10/965,024, filed Oct. 15, 2004 (nowU.S. Pat. No. 7,274,913), all of which are incorporated by referenceherein in their entireties.

BACKGROUND

1. Field

The present invention is related to transceiver systems and methods, andmore particularly to radio frequency transceivers.

2. Background Art

Recently, transceivers have most input/output (I/O) components locatedoff-chip on a printed circuit board, or the like. However, this can leadto a large number of external components (i.e., components external tothe chip), more complexity, and higher costs.

Therefore, what is needed is a single chip having an integratedtransceiver I/O components that can be internally configured to reduce anumber of external components.

SUMMARY

One embodiment of the present invention provides a transceiver system.The transceiver system includes a bias source, a transformer, and aswitching device. The transformer includes a primary side and asecondary side. During a receive mode, the primary side is configured toreceive a first signal at a first port. During a transmission mode, theprimary side is configured to transmit a second signal from a secondport. The switching device is configured to couple the first port to thebias source during transmission of the second signal and to couple thesecond port to the bias source during receipt of the first signal.

Further embodiments, features, and advantages of the present inventions,as well as the structure and operation of the various embodiments of thepresent invention, are described in detail below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, further serve to explainthe principles of the invention and to enable a person skilled in thepertinent art to make and use the invention.

FIG. 1 shows a transceiver system having a single mode I/O portion,according to one embodiment of the present invention.

FIG. 2 shows a transceiver system having a single mode I/O portion,according to one embodiment of the present invention.

FIG. 3 shows a transceiver system having a single mode I/O portion,according to one embodiment of the present invention.

FIG. 4 shows a transceiver system having a multiple mode I/O portion,according to one embodiment of the present invention.

FIG. 5 shows a transceiver system having a multiple mode I/O portion,according to one embodiment of the present invention.

FIG. 6 shows a transceiver system having a multiple mode I/O portion,according to one embodiment of the present invention.

FIG. 7 shows a transceiver system having a multiple mode I/O portion,according to one embodiment of the present invention.

The present invention will now be described with reference to theaccompanying drawings. In the drawings, like reference numbers mayindicate identical or functionally similar elements. Additionally, theleft-most digit(s) of a reference number may identify the drawing inwhich the reference number first appears.

DETAILED DESCRIPTION

Overview

While specific configurations and arrangements are discussed, it shouldbe understood that this is done for illustrative purposes only. A personskilled in the pertinent art will recognize that other configurationsand arrangements can be used without departing from the spirit and scopeof the present invention. It will be apparent to a person skilled in thepertinent art that this invention can also be employed in a variety ofother applications.

Embodiments of the present invention provide a transceiver chipcomprising and operational section and an input/output section. Theoperational section includes a controller. The input/output (I/O)section is coupled to the operational section. The I/O section comprisesa transformer and a switching device including first and secondtransistors. The transformer includes a primary side connected to firstand second I/O ports and a secondary side connected to the operationalsection. The switching device is coupled to the controller and betweenthe first and second I/O ports and a bias port. After choosing an I/Oport to be used, the controller causes the switching device to connectone of the first and second I/O ports to the ground port. This can bedone through turning ON or OFF of a respective one of the first andsecond transistors. Turning OFF of the transistor causes an open circuitbetween a chosen I/O port and the bias port and turning ON of thetransistor causes a short circuit between the non-chosen I/O port andthe bias port.

The transmission medium can be, but is not limited to wire or wirelesstransmission, or any other form of transmission, as would becomeapparent to one of ordinary skill in the art upon reading thisdescription.

Transmission signals can be, but are not limited to, baseband,modulated, frequency band, or similar signals, as would become apparentto one of ordinary skill in the art upon reading this description.

Throughout this description, a transmitted signal or a device processinga transmitted signal (e.g., a signal being transmitted from the chip viaan antenna) is designated T or TX and a received signal or a deviceprocessing a received signal (e.g., a signal received at an antenna andbeing transmitted to the chip) is designated R or RX.

Throughout this description a “chip” is considered a small piece ofsemi-conducting material (e.g., silicon) on which an integrated circuitis embedded, which can contain millions of electronic components (e.g.,transistors). For example, the chip can be, but is not limited to, CPUchips (i.e., microprocessors), memory chips, single in-line memorymodules (SIMMs), dual in-line memory modules (DIMMs), and the like,which can be in one of many known packages. For example, a package canbe, but is not limited to, a DIPs (Dual in-line packages), PGAs(Pin-grid arrays), SIPs (Single in-line packages).

Exemplary Single Mode I/O Section for a Transceiver

FIG. 1 shows a system 100. In one example, system 100 is a transceiversystem or a radio frequency (RF) transceiver. System 100 includes aboard 102 (e.g., a printed circuit board (PCB) or the like) coupled to achip 104 coupled to board 102. The coupling can be accomplished throughany known coupling technique, for example, but not limited to, via apackage structure as described above, a leadframe, or the like, as wouldbecome apparent to one of ordinary skill in the art.

Board 102 includes an antenna 106, a switch 108 (e.g., atransmit/receive (TR) switch), and first and second match/Balun devices110 and 112. First and second match/balun devices 110 and 112 areconnected to first and second ports 114 and 116, respectively, of chip104. In the example shown, first port 114 is a RX port (receiving port)and second port 116 is a TX port (transmitting port) of chip 104. Inthis example, a signal received at antenna 106 is routed via switch 108through match/Balun device 110 to first port 114 of chip 104. A signalbeing transmitted from chip 104 via second port 116 is transmittedthrough match/Balun device 112 and routed using switch 108 to antenna106 for transmission.

The match sections of respective match/balun devices 110 and 112 areused as impedance matching networks between antenna 106 and chip 104.The balun section in match/balun device 110 is used to convert asingle-ended received signal from antenna 106 to a differential signal,while a balun section in match/Balun device 112 is used to convert adifferential signal from chip 104 to a single ended signal to betransmitted by antenna 106. The match/balun circuit is well known in thetransceiver art.

Chip 104 comprises an I/O section 118 and an operational section 120. Inthis example, I/O section 118 comprises first and second ports 114 and116. Operational section 120 comprises a first amplifier 122 (e.g., alow noise amplifier (LNA)) connected to first port 114 and a secondamplifier 124 (e.g., a power amplifier (PA)) connected to second port116. Integrated LNA and PA are well known in the transceiver art.

First amplifier 122 is used to amplify a RX signal received at firstport 114, which is then transmitted to mixer 126. A frequency of the RXsignal is down converted using frequency f_(LO) before being processedby other devices (not shown) in operational section 120.

Second amplifier 124 is used to amplify a TX signal being transmittedout second port 116 by chip 104. A frequency of the TX signal is firstup converted using mixer 128 and frequency f_(LO) before being amplifiedusing second amplifier 124. In one example, the transmission signal TXoriginates in a device in operational section 120 of chip 104.

However, in order to lower a total cost of system 100, it is desirableto reduce a number of components external to chip 104, i.e., componentson board 102.

FIG. 2 shows a system 200. In one example, system 200 is a transceiversystem or a radio frequency (RF) transceiver. System 200 includes aboard 202 and a chip 204. Board 202 includes an antenna 206. Chip 204includes an I/O section 218 and an operational section 220.

I/O section 218 of chip 204 includes a transformer 230. A first end 232of a primary side 234 of transformer 230 is coupled to a TX/RX port 236through a wire bond 238, whose characteristic inductance is shown as L2.A second end 240 of primary side 234 is coupled to a port 242 through awire bond 254, whose characteristics inductance is shown as L3. In thisexample, port 242 is coupled to ground (GND) or bias source VSS on board202. A center tap of a secondary side 246 of transformer 234 is coupledto a port 248 through a bond wire 250, whose characteristic impedance isshown as L1. In this example, port 248 is coupled to a bias source VDDpossibly on board 202 or otherwise located. In this example, the centertap of secondary side 246 of transformer 230 is coupled to bond wire 250via a node or bond pad 260.

In one example, in order to offset the inductances L2 and L3 capacitorsC1 and C2 are used, respectively, which should result in a desiredimpedance (e.g., 50 Ω) looking into ports 236 and 242. Capacitor C1 iscoupled at node or bond pad 252 to bond wire 238 and to first end 232 ofprimary side 234 of transformer 230. Capacitor C2 is are coupled at nodeor bond pad 254 to bond wire 244 and to second send 240 of primary side234 of transformer 230.

In one example, an additional bond wire 256 is coupled to a port 258 anda node or bond pad 259. This additional bond wire can be used to connecta desired portion of I/O section 218 or operational section 220 to port258, i.e., to ground (GND) on board 202.

In system 200, an I/O section 218 is used to integrate TR-switchfunctionality, single-ended to differential conversion, and matching.The TR switch functionality is achieved by connecting LNA inputs 262 andPA outputs 264 together. By adjusting an ON and OFF state of LNA/PAimpedances, a PA output signal is not dissipated in LNA 222 in TX modeand a receive signal is not dissipated in PA 264 in RX mode.

In one example, in operational section 220 a combined LNA/PAdifferential port 266 is connected to secondary side 246 of atransformer 230. This configuration serves at least two purposes: 1)differential to single-ended conversion and 2) to provide impedancematching. Differential to single-ended conversion is achieved bygrounding second end 240 of primary side 234 of transformer 230 andusing port 236 as a RF-I/O port. Also, by accurately adjusting theparameters of transformer 230, such as turns ratio Ls/Lp and Qualityfactor (Q) with all the parasitic components taken into account,transformer 230 can be designed to provide the desired impedance matchat port 236.

At higher frequencies, package non-idealities, such as bond wireinductances L1-L4 and parasitic capacitances, influence RF performanceand have to be taken into account. In the arrangement shown, bond wiresinductances L2 and L3 and series capacitors C1 and C2 may form seriesresonant circuits that resonate at a frequency of interest and provide alow impedance path from respective ports 236 and 242 to transformerprimary side 234.

FIG. 3 shows a system 300. In one example, system 300 is a transceiversystem or a radio frequency (RF) transceiver. A main difference betweensystems 200 and 300 is that a board 302 in system 300 includes amultiplexing system 368 between an antenna 306 and port 236.Multiplexing system 368 includes first and second switches 370 and 372,respectively, and an amplifier 374 (e.g., a power amplifier (PA)).

A first path 371 (e.g., an RX path) through multiplexing system 368allows a received signal from antenna 306 to be transmitted to port 236when both switches 370 and 372 are in their down position.

A second path 373 (e.g., a TX path) through multiplexing system 368allows a signal from port 236 to be transmitted via PA 374 to antenna316 when both switches 370 and 372 are in their up position.

In some applications it is desirable to have separate access to the TXand RX ports, but without sacrificing the high level of integrationshown in FIG. 2. For example, in certain applications a higher outputpower may be required and chip 204 has to accommodate an external PA 374(i.e., a PA external to chip 204). Thus, the topology in FIG. 2 ismodified in order to provide the separate TX and RX paths, describedabove, through multiplexer 368. External PA 374 will then be insertedinto the TX path.

Exemplary Multi-Mode I/O Section for a Transceiver

As discussed above, it is desirable to reduce a number of components onan external board (i.e., a board external to a chip), while allowing formulti-mode (TX and RX) functionality. The following embodiments allowfor multi-mode operation of a chip's I/O circuit through dedicatedports, while integrating the multi-mode functionality on the chip.

FIG. 4 shows a system 400. In one example, system 400 is a transceiversystem or a radio frequency (RF) transceiver. A main difference betweensystem 400 and previous systems described above is that an I/O section418 of chip 404 includes a switching device 476 and an operationalsection 420 of a chip 404 includes a controller 478. In thisconfiguration, switching device 476 is controlled by a controller 478 tocontrol which of ports 436 or 442 are active ports (e.g., able to sendor receive signals) and which of ports 436 or 442 are inactive ports(e.g., grounded or biased so as not to receive or transmit signals).

Switching device 476 is coupled between pads or nodes 452 and 454 and aport 458. In this example, port 458 is coupled to ground. Node 452 ispositioned between a port 436 (e.g., an I/O port) and a first end 432 ofa primary side P 432 of a transformer 430. Node 454 is positionedbetween a port 442 (e.g., an I/O port) and a second end 440 of primaryside P 432 of transformer 430. In this example, through control signalsfrom controller 478, switching device 476 grounds or otherwise biasesone of ports 436 or 442, allowing the ungrounded port to transmit orreceive signals.

In the implementations discussed above in relation to FIGS. 1-3, one ofthe transformer primary ports is used as an RF-I/O and the other primaryport always needs to be grounded, which is done externally on the PCB.In contrast, in the embodiment shown in FIG. 4, a multi-modeimplementation is shown in which either of the primary ports 436 or 442can be internally selectable, using switch 476 and controller 478, as anRF-I/O terminal.

It is to be appreciated that one or more components in system 400 can beprogrammable software or firmware.

In another example, switching device 476 is coupled between nodes 452and 454 and node 460, i.e., to a bias port 448. In this example,switching device 476 is not coupled to port 458 at all. Bias port 448 iscoupled to a power source (not shown), which is located either on aboard 402, or otherwise located. In this example, through controlsignals from controller 478, switching device 476 biases one of ports436 or 442 via bias port 448, allowing the unbiased port to transmit orreceive signals

FIG. 5 is a schematic diagram of system 400 in FIG. 4. In thisembodiment, switching device 476 includes first and second transistors582 and 584. In one example, first and second transistors 582 and 584are NMOS-transistors M1 and M2, respectively, that act as switches thatconnect at their drains to respective ones of nodes 452 and 454 and attheir sources to port 458.

In this example, the operation of system 400 is as follows. To enableport 436 as the RF-I/O, a LOW control signal or gate voltage V1 fromcontroller 478 biases first transistor 582 and a HIGH control signal orgate voltage V2 from controller 478 biases second transistor 584. Inthis state, transistor 582 is OFF or open. Also, in this state,transistor 584 is ON or shorted, which essentially grounds port 442through coupling port 442 to node 458.

Similarly, to enable port 442 as the RF-I/O, gate voltage V1 is HIGH andgate voltage V2 is LOW. In, this state transistor 582 is ON or shorted,which essentially grounds port 436 through coupling port 436 to node458. Also, in this state, transistor 584 is OFF or open.

In one example, as seen in FIG. 5, at a secondary side 446 oftransformer 430 there is no theoretical restriction to a number of portsor tapping points that can be used. In the example shown, symmetric portpairs S1-S2 and S3-S4 are shown. For example, if differenttransformation ratios are required between the LNA and PA, a LNA (notshown) may be connected to ports S1-S2 and a PA (not shown) may beconnected to ports S3-S4.

In one example, in order to achieve a desired performance for system 400(e.g., best symmetry and lowest insertion loss and noise figure), thegrounded port has as low an impedance as possible at a frequency ofinterest. This can result in an increased W/L (width to length ratio, orsize) of the NMOS switches 582 and 584, but usually parasiticcapacitances associated with switches 582 and 584 will set an upperlimit of W/L. The sources of switches 582 and 584 also need to connectto a good ground GND on board 402 through port 458.

It is to be appreciated that with this scheme, when both V1 and V2 areLOW both transistors 582 and 584 are OFF, neither of ports 436 or 442will be grounded and transformer 430 can be used similar to transformer230 in system 200 of FIG. 2.

In the example discussed above (not shown in FIG. 5), when switchingdevice 476 is coupled between nodes 452 and 454 and node 460, and not tobias port 458, switching device 476 includes two PMOS transistors withtheir drains coupled to node 460 and their sources connected torespective ones of nodes 452 and 454. In this example, operation ofswitch 476 would be modified to reflect the functionality of PMOSdevices versus NMOS devices, as would become apparent to one of ordinaryskill in the art upon reading this description.

FIG. 6 shows a system 600. In one example, system 600 is a transceiversystem or a radio frequency (RF) transceiver. System 600 includes aboard 602 comprising an antenna 606, a switch 670, and an amplifier 674.Switch 670 routes a signal from antenna 606 to node 642 when system 600is in RX mode, and switch 670 routes a signal from node 636, throughamplifier 674, and to antenna 606 when system 600 is in TX mode.

System 600 is similar to a combination of system 300 shown in FIG. 3 andsystem 400 shown in FIGS. 4-5, with a difference being that because theRF-I/O port now can be alternated between ports 636 and 642, oneexternal TR-switch (e.g., 372) can be removed. In the example shown inFIG. 6, port 636 is used for a TX output and port 642 is used for a RXinput. In one example, a switching device 676 includes NMOS transistors682 and 684. Thus, in this example, for TX output active V1=LOW andV2=HIGH and for RX input V1=HIGH and V2=LOW.

It is to be appreciated, as described above, PMOS transistors could alsobe used in switching device 676 if its coupling was modified in I/Oportion 618.

Another difference between system 600 and the combination of systems 200and 400 is that in system 600 ground GND on board 602 does not providelow impedance paths to chip 604. Thus, chip 604 includes an additionalport 680 (e.g., a RFTUN pin or RF tuning pin) that is used to tune theground at the sources of transistors 682 and 684 to achieve a lowestpossible impedance at a desired frequency. This is accomplished throughthe use of a series resonant circuit 686. Circuit 686 comprises abond-wire 688, whose characteristic is shown as inductance L5, andcapacitor C3. Capacitor C3 is coupled between a bond pad or node 690 anda node 659. Node 659 couples the sources of transistors 682 and 684 to abond wire 656 that is connected to ground through node 658. Capacitor C3is an adjustable capacitor that is adjusted to tune the ground. In oneexample, the adjustment is performed via programming of capacitor C3after chip 604 is manufactured or after the chip is packaged, as isdiscussed above. Capacitor C3, similar in function to capacitors C1 andC2, is used to offset inductance L5 to produce a zero impedance lookingat sources 682 and 684.

In one example, a bypass capacitor C4 is coupled between a center tap ofa secondary side 632 of transformer 630 and node 659. The transformer630 further contains a primary side 634. In this arrangement, capacitorC4 further improves the ground by capacitively effectively coupling L1and L4 in parallel.

FIG. 7 shows system 700. In one example, system 700 is a transceiversystem or a radio frequency (RF) transceiver. A main difference betweensystem 700 and system 600 is that a one antenna system of system 600 isreplaced with a two antenna system in system 700. Thus, in system 700 aboard 702 includes a first antenna 706A coupled to a node 736 and asecond antenna 706B coupled to a node 742. It is to be appreciated thatwhich antenna 706A or 706B to use, either for RX or TX, is controlled bygate voltages V1 and V2 of transistors 782 and 784. Otherwise, thissystem 700 operates similar to systems 400 and 600 described above.

Conclusion

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not limitation. It will be apparent to persons skilledin the relevant art that various changes in form and detail can be madetherein without departing from the spirit and scope of the invention.Thus, the breadth and scope of the present invention should not belimited by any of the above-described exemplary embodiments, but shouldbe defined only in accordance with the following claims and theirequivalents.

1. A transceiver system, comprising: a bias source; a transformerincluding a primary side and a secondary side, wherein during a receivemode the primary side is configured to receive a first signal at a firstport and during a transmission mode the primary side is configured totransmit a second signal from a second port; and a switching deviceconfigured to couple the first port to the bias source duringtransmission of the second signal and to couple the second port to thebias source during receipt of the first signal.
 2. The transceiversystem of claim 1, further comprising: a transmitter port; a firstinductor-capacitor (L-C) network coupled between the transmitter portand the second port, wherein the first L-C network is configured tooffset a first inductance in a transmission path; a receiver port; and asecond L-C network coupled between the receiver port and the first port,wherein the second L-C network is configured to offset a secondinductance in a receive path.
 3. The transceiver system of claim 1,wherein the bias source comprises ground.
 4. The transceiver system ofclaim 1, wherein the bias source comprises a tuning network configuredto adjust a ground terminal of the switching device to substantiallyground.
 5. The transceiver system of claim 4, wherein the tuning networkcomprises an L-C network configured to adjust a value of a capacitor inthe L-C network.
 6. The transceiver system of claim 1, wherein: duringthe receiving mode, the transformer is configured to convert asingle-ended version of the first signal to a differential-ended versionof the first signal; and during the transmission mode, the transformeris configured to convert a double -ended version of the second signal toa single-ended version of the second signal.
 7. The transceiver systemof claim 6, wherein: during the receiving mode, the secondary side ofthe transformer is configured to receive the single-ended version of thefirst signal from the primary side; and during the transmission mode,the secondary side of the transformer is configured to transfer thedifferential-ended version of the second signal to the primary side. 8.The transceiver system of claim 1, wherein the switching device isconfigured to couple the first port to the bias source after activationof a first transistor device or to couple the second port to the biassource after activation of a second transistor device.
 9. Thetransceiver system of claim 8, wherein the activation of the first andsecond transistor devices comprises coupling of the bias source to thefirst port or second ports, respectively.
 10. An integrated circuit (IC)transceiver, comprising: an operational section including a firstamplifier and a second amplifier, wherein the first amplifier isconfigured to amplify a first signal and the second amplifier isconfigured to amplify a second signal; a transformer including a primaryside and a secondary side, wherein during a receive mode the secondaryside is configured to receive the first signal from the primary side andduring a transmission mode the secondary side is configured to transferthe amplified second signal to the primary side; and a switching deviceconfigured to selectively couple one or more ports of the primary sideto a bias source during a receipt of the first signal by the transformerand a transmission of the amplified second signal from the transformer.11. The IC transceiver of claim 10, wherein the first amplifier isconfigured to, during the receive mode, receive a differential-endedversion of the first signal and the second amplifier is configured to,during the transmission mode, amplify a differential-ended version ofthe second signal.
 12. The IC transceiver of claim 11, wherein thesecondary side is configured to, during the receive mode, transfer thedifferential-ended version of the first signal to the first amplifierand to, during the transmission mode, receive the amplifieddifferential-ended version of the second signal from the secondamplifier.
 13. The IC transceiver of claim 10, wherein the switchingdevice is configured to couple a first port of the primary side to thebias source during transmission of the amplified second signal and tocouple a second port of the primary side to the bias source duringreceipt of the first signal.
 14. The IC transceiver of claim 10, whereinthe bias source comprises ground.
 15. The IC transceiver of claim 10,wherein the bias source comprises a tuning network configured to adjusta ground terminal of the switching device to substantially ground.
 16. Atransceiver system, comprising: a first antenna; a second antenna; atransformer including a primary side and a secondary side, wherein theprimary side is configured to receive a first signal from the firstantenna along a receive path and to transmit a second signal with thesecond antenna along a transmission path; and a switching deviceconfigured to couple the first antenna to a bias source duringtransmission of the second signal and to couple the second antenna tothe bias source during receipt of the first signal.
 17. The transceiversystem of claim 16, further comprising: a first inductor-capacitor (L-C)network coupled between the second antenna and the primary side, whereinthe first L-C network is configured to offset a first inductance in thetransmission path; and a second L-C network coupled between the firstantenna and the primary side, wherein the second L-C network isconfigured to offset a second inductance in the receive path.
 18. Thetransceiver system of claim 17, wherein the transformer is configured toconvert a single-ended version of the first signal and a single-endedversion of the second signal to a corresponding differential-endedversion of the first signal and a differential-ended version of thesecond signal.
 19. The transceiver system of claim 18, wherein thesecondary side is configured to receive the single-ended version of thefirst signal from the primary side and to transfer thedifferential-ended version of the second signal to the primary side. 20.The transceiver system of claim 16, wherein the switching device isconfigured to couple the first antenna to the bias source via activationof a first transistor device and to couple the second antenna to thebias source via activation of a second transistor device.